The worldwide dramatic decline in infant mortality is perhaps the most widespread and significant social change of the past century. How this transformation has taken place -- globally and locally -- remains a question of great importance to students of society and policy makers, as reflected in the scholarly debates over the role, magnitude, and interaction of economic growth, improvements in medical care, nutrition, public health measures, migration, ecological changes, and private hygiene practices in the modem mortality decline. Despite the relevance of such longitudinal analyses of population dynamics to developing countries, there have been virtually no detailed studies of pre-1940 mortality declines outside of North America, Europe, and Japan. This study proposes to begin to address this gap in knowledge by examining infant mortality patterns in one setting in South America --Uruguay from 1882, when the national vital statistics registry began, until 1950. The availability of 19th century vital statistics publications, extensive social statistics, and primary archival sources in Uruguay makes it a rare population "laboratory." In confronting this research problem, the study develops an integrated methodology that combines established historical demography approaches with an iterative historical-epidemiological feedback loop to examine the evolution of disease-specific and general infant mortality in Uruguay, estimating the relative contribution of a series of social, political, economic, geographic, cultural, and medical variables on infant mortality. The investigators hypothesize that infant mortality is more closely correlated with indicators of social inequality than with aggregate levels of income, economic development, and medical advancements. The results of this analysis will be useful to policy makers, scholars, and public health audiences in the U.S., Latin America, and other regions who are interested in the determinants of infant mortality.